1. Field of Invention
The present invention relates to a cutting and transport roller as well as a process for controlling the seating pattern of a material web on the peripheral surface of the roller.
2. Description of the Prior Art
A cutting and transport roller of this type is known from the patent application EP 0 698 671 A1. The roller described there comprises of an inner hollow space into which a separating body is inserted. This separating body and the outer shell of the roller delimit pressure rooms. The pressure rooms are in contact with the ambient by means of a penetrating borehole in the peripheral surface of the roller. The pressure rooms can be connected to the sources of high pressure and low pressure arranged outside the roller by means of pressure media lines so that, if necessary, a state of high pressure or low pressure is created in the pressure rooms that acts on the material web running on the peripheral surface of the roller. Thus the material web is either laid down (low pressure) to the roller or pushed away (high pressure) from it.
The roller described is generally used in winding devices for winding up material webs. In such a device the material web has to be severed after a complete roll is formed and the start of the new web is placed on a new winding core. Cutters are used for the purpose of cutting the web. These cutters are even integrated into the roller in newer winding devices. One such cutter is described, for instance, in the patent application DE 100 47 545 A1. The cutting elements of these cutters briefly pass through the peripheral surface of the roller and thus cut through the material web. At the same moment low pressure is applied to the pressure rooms so that the material web is held on to the roller. If the start of the web now reaches the new winding core, then high pressure is applied to the pressure rooms. Consequently, the material web is pushed away from the roller and onto the winding core. This process is referred to as the initial winding process.
The cutting and transport roller described in the patent application EP 0698 671 A1 comprises of voluminous hollow spaces in its interior through which the media conveying the pressure—usually air, of course—are supplied to the media outlet openings. Here these media are supplied to the roller by the so-called ‘pressure sources,’ which can be pumps, for instance.
In practice, it has been seen that the processes of laying down the material web on the roller and/or pushing it away from the roller do not take place reliably at high peripheral speed using the device described.